Physical and electrochemical evaluation of ATO supported IrO_2 catalyst for proton exchange membrane water electrolyser

摘要

Antimony doped tin oxide (ATO) was studied as a support material for IrO_2 in proton exchange membrane water electrolyser (PEMWE). Adams fusion method was used to prepare the IrO_2-ATO catalysts. The physical and electrochemical characterisation of the catalysts were carried out using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder conductivity, cyclic voltammetry (CV) and membrane electrode assembly (MEA) polarisation. The BET surface area and electronic conductivity of the supported catalysts were found to be predominantly arisen from the IrO_2. Supported catalyst showed higher active surface area than the pristine IrO_2 in CV analysis with 85% H_3PO_4 as electrolyte. The MEA performance using Nafion~®-115 membrane at 80 ℃ and atmospheric pressure showed a better performance for IrO_2 loading ≥60 wt.% than the pristine IrO_2 with a normalised current density of 1625 mA cm~(-2) @1.8 V for the 60% IrO_2-ATO compared to 1341 mA cm~(-2) for the pristine IrO_2 under the same condition. The higher performance of the supported catalysts was mainly attributed to better dispersion of active IrO_2 on electrochemically inactive ATO support material, forming smaller IrO_2 crystallites. A 40 wt.% reduction in the IrO_2 was achieved by utilising the support material.